What makes an AP class “hard”? Some have very difficult subject matter AND are time consuming (have a lot of homework). I’d put AP Calculus BC in that category, along with AP Physics C. Others require a lot of time, but the subject matter isn’t that hard (APUSH), but it’s still a hard class because of the two hours of homework each night (in DD’s HS). Others depend on your abilities and interests (the AP CS classes are extremely time consuming, but whether or not you find them difficult depends on your skills and interests). In our school, AP Enviro Science, AP Seminar, and AP Human Geography are fluff classes.
Bottom line is that, with a few exceptions (like Calculus BC), each school is going to be different. Your best bet is to talk to the teachers of those classes, talk to your GC, and talk to some students who have taken the class before. Armed with that information, you can make a plan that challenges you, but gives you a decent chance at success.